Unidirectional valve for anesthesia equipment



Jain. 13, 1959 5. BROOKE 2,868,198

UNIDIRECTIONAL VALVE FOR ANESTHESIA EQUIPMENT Filed March 9, 1956 2Sheets-Sheet 1 INVENTOR. BURNHAM BROOKE A fern eys Jan. 13, 1959 B.BROOKE 2,868,198

UNIDIRECTIONAL VALVE FOR ANESTHESIA EQUIPMENT Filed March 9, 1956INVENTOR. BURN HAM BROOKE '2 Sheets-Sheet 2 United States PatentUNIDIRECTIONAL VALVE FOR ANESTHESIA EQUIPMENT Burnham Brooke, Portland,Oreg. Application March 9, 1956, Serial No. 570,576 9 Claims. (Cl.128-188) This invention relates to a unidirectional anesthesia valve foruse with a conventional face mask or endotracheal tube.

Although the present invention may be used with various apparatus, it isillustrated herein as equipment more efliciently to administer aninhalation anesthetic to a patient. Equipment for administeringinhalation anesthetics by the commonly known method of circle breathingcomprises principally a face mask, a canister to remove exhaled carbondioxide, a breathing bag, anesthetic containing means, and suitabletubing and valve structure, and the desired function is to supply saidanesthetics to patients in suitable amount and in a manner to producesmooth breathing with a minimum of resistance to the breathing effortsof the patient. In any given respiratory effort a certain portion of airlodges in the dead space of the respiratory tract and is consequentlyineffective as a means of modifying the gas content of alveolar air. Inpatients who have relatively large tidal Volumes, such as strong, grownpersons, the administration of anesthetics does not raise criticalproblems because the tidal volume exceeds the combined volume of themechanical and physiologic dead spaces, whereby even though there isre-breathing of a certain volume of exhaled gases, sufiicient freshgases, including the anesthetic, will be inhaled.

The mechanical dead space is the dead space in the apparatus, such as inthe mask, and the physiologic dead space is the dead space in the humancomprising the combined volume of the nasobucco pharynx, trachea andbronchi. In patients having a small tidal volume, such as children oraged and weak persons, or in patients where the tidal volume is reducedby drugs, major problems arise in administering an anesthetic becausethe tidal volumes in these types of patients frequently do not exceedthe mechanical and physiologic dead spaces. In such case there is anoscillation of excess exhaled gases in the mechanical and physiologicdead spaces whereby untreated exhaled gases are re-breathed to producethe undesirable physiological disturbances caused by excesscarbon-dioxide retention. Heretofore, circle breathing has beenimpractical in children below seven years of age because the volume ofdead space in the apparatus has been excessive.

The physiologic dead space, or dead space of the respiratory tract in anadult man, is approximately 150 cc., and is correspondingly smaller inchildren and infants. The tidal volume of a man at rest is approximately500 cc., and correspondingly smaller as the chest size decreases.v"There is a wide variation in tidal volume not only from subject tosubject but also from moment to mo'mentin the same subject. Under suchvariable conditions, minimizing the re -breathing of exhaled gases alsoinvolves conflicting problems in minimizing the backlash of gases andresistance to flow, particularly through the valves.

The principal object of the present invention is to provide an improvedvalve unit to minimize as much as possible the re-breathing of untreatedexhaled gases in anesthesia equipment to and reduce resistance torespiratory efiort.

Another object is to provide an improved valve unit which makes thecircle breathing method of administering anesthetics practical for useon children.

More specific objects of the invention are to provide a valve unithaving a compact arrangement of passageways and chambers for reducing toa minimum the mechanical dead space therein; to provide a valve unit foruse with a face mask or endotracheal tube, which employs valves locatedclosely adjacent the face mask or endotracheal tube to reduce to aminimum the dead space between the valves and the patient; and toprovide a novel valve unit and arrangement which is quickly responsiveto gas flow for efiiciently controlling the flow of anesthetic andexhaled gases.

Another object is to provide an improved valve unit which may beembodied in equipment for children and infants, as well as for adults.

Another object is to provide a valve unit of the type described which isadapted for a quick exchange from a face mask to endotracheal tubeduring the procedure of intubation.

Another object is to provide a valve unit of the type described which istransparent to permit observation of the functioning of the valves,which is readily washable, and which is relatively simple andinexpensive to manufacture.

The objects stated above are carried out by a oneway valve unit adaptedto be used in conjunction with the necessary anesthesia equipmentcomprising a face mask, inhalation and exhalation tubes, a canister, abreathing bag, anesthetic containing means, and oxygen supply means. Theinhalation and exhalation tubes communicate with separate valvepassageways which communicate with a common breathing chamber throughinlet and outlet mushroom valves mounted in a wall between the separatevalve passageways and the breathing chamber. One of the walls definingthe breathing chamber has an opening leading into said chamber whichfrictionally receives either a fitting on the face mask or a fitting onan endotracheal tube. As will be pointed out in greater detailhereinafter, the valve unit assumes a structure which minimizes as muchas possible the rebreathing of untreated exhaled gases, whereby a smallvolume inhalation will bring the anesthetic into the patients lungs.

The invention will be better understood and additional objects andadvantages will become apparent from the following description taken inconnection with the accompanying drawings which illustrate a preferredform of the invention. It is to be understood, however, that theinvention may take other forms, and that all such modifications andvariations within the scope of the appended claims, which will occur topersons skilled in the art, are included in the invention.

In the drawings:

Figure 1 is a perspective view of the present invention and otherequipment for administering an anesthetic;

Figure 2 is a top plan view of the present valve unit with 'a portion ofthe valve housing broken away;

Figure 3 is an enlarged cross sectional view taken approximately on theline 33 of Figure 2;

Figure 4 is a bottom plan view of the valve unit;

Figure 5.is a cross sectional view taken on the line 5-5 of Figure 3;

Figure 6 is a side elevational view of the valve unit, and showingbottom connections for an endotracheal tube;

Figure 7 is a sectional view of an outlet valve used in conjunction withthe present valve unit;

Figure 8 is a perspective view of a slightly modified form of thepresent valve unit for small children;

Figure 9 is a bottom plan view of the embodiment of Figure 8; and

Figure 10 is a cross sectional view taken on the line 10-10 of Figure 8.a 7

Referring to the drawings, Figure '1 shows equipment for administeringanesthetic to a patient. The equipment shown comprises a breathingcircuit composed of a breathing bag 10, a soda-lime canister 11supported on a standard 12 for absorbing carbon dioxide, an exhalationtube 13, an inhalation tube 14, a face mask 15 having suitable strapmeans 16 for securing it on the patients head, and a valve unit 17 whichforms the present invention. This equipment also has ether-oxygenapparatus comprising principally an ether bottle 18 and an oxygen tank19 connected to the valve unit 17 by a tube 20. The exhalation tube 13is connected between the valve unit 17 and one end of the canister 11,and the other tube 14 is connected between the valve unit and thebreathing bag 10, the discharge end of the canister being connected incircuit with the tube 14 so that treated exhaled gases being dischargedfrom the canister 11 are rebreathed by the patient. The purpose of thevalve unit 17 is to produce circulatory flow in the direction of thearrows and to minimize the rebreathing of untreated exhaled gases.

The valve unit 17 comprises a composite housing having an upper housingportion 21, a lower housing portion 22, and in intermediate wall or portplate 23. The upper portion 21 of the housing comprises a pair ofparallel longitudinal passageways 24 and 25 defined at the upper portionthereof by semi-cylindrical Wall portions 26 and 27, respectively,closed at one end by a wall 28. At the opposite end of the valve unit isa wall 29, and integrally mounted in this wall are connecting tubeportions 30 and 31 which communicate with the passageways 24 and 25,respectively, and which are adapted to receive by a frictional fit theexhalation tube 13 and the inhalation tube 14.

The port plate 23 forms the bottom wall of passageways 24 and 25 and hasa pair of outlet ports 35 disposed in communication with the passageway24 and a pair of inlet ports 36 disposed in communication with thepassageway 25. Each of the ports 35 and 36 is bridged by a spiderportion 38 forming a portion of the wall 23. Each spider 38 has acentral hub portion 39 provided With an aperture 40.

Associated with the outlet ports 35 are valves 42, and associated withthe inlet ports 36 are valves 43. Each valve comprises a thin, fiat discof flexible rubber having an integral stem 45 and a reduced neck portion46. Neck portion 46 is locked in the aperture whereby the centralportion of the valve is anchored, but, due to the flexibility of thevalve, portions thereof spaced from the center are readily flexed awayfrom its seat by a relatively slight firessure difierential on oppositesides of the mushroom Disposed below the wall 23 in the lower portion 22of the valve housing is a chamber 48 which communicates with all theports 35 and 36. Referring to Figure 5, the shape of the chamber 48 isshown in plan and com prises a pair of semi-circular wall portions 49 onthe inlet port side and a pair of semi-circular wall portions 50 on theoutlet port side. Wall portions 49 assume a shape slightly larger thanthe valves 43 to permit free operation thereof, and Wall portions 50assume a shape which. follows substantially the contour of a portion ofoutlet ports 35. The chamber 48 has projecting portions 51 which fill inportions of the spaces between adjacent valves.

Referring to Figure 3, which shows the chamber 48 in cross section,defining wall 49 is substantially straight and vertical and the wall 50is curved. The shape of the chamber 48, as described, is such as toassume as small a volume as possible to minimize dead space in whichuntreated exhaled gases may oscillate and yet is large enough to permitthe free operation of 'the valves and to permit sufficient flow of gasestherethrough without appreciable impedance. Chamber 48 constitutes themechanical dead space in the valve unit which must be added to themechanical dead space in the face mask or endotracheal tube. In thevalve unit shown in Figures 2 and 3 the dead air space has been reducedto 10 cc. In conventional practice a Y-chimney piece or other fittinghaving considerable volume is added to the dead space of the mask.

Communicating with the chamber 48 is a bottom opening 52 adapted toreceive, by a frictional fit, a connector 53 on the face mask 15, theupper portion of the wall defining the opening 52 being rounded toprovide in conjunction with chamber 48 a streamlined flow of gases. Asan alternative, and as seen in Figure 6, the opening 52 may frictionallyreceive an adaptor connector 55 which in turn frictionally receives aconnector 56 on an endotracheal tube 57, whereby, as is the usual customin certain cases the patient is first put to sleep by use of the maskand then subsequently, the tube 57 is substituted for the mask. Suchinterchangeability of the patient-engaging piece is thus readily andconveniently accomplished by disengagement of the valve 17 with theconnector for the desired piece without disconnecting any of the tubes13, 14 or 20. Although not shown on the drawings, the standardendotracheal tube 57 may be equipped with an inflatable cult adjacentits bottom end for sealing off the subjects trachea when the tube 57 isinserted.

An outlet valve 60 is provided in the wall 26 of passageway 24, and thisvalve comprises a housing 61 having external threads 62 engageable in athreaded boss 63 which forms an integral part of the wall 26. A turningstem 64 is threadedly mounted in the housing 61 and urges a valve 65 bymeans of a spring 66 into sealing engagement with a port 67 on thebottom of the housing. The turning stem 64, valve 65 and spring 66 arepreferably connected together so that, by unscrewing the stem 64,sufficient tension is taken off the valve so that it will be disengagedfrom its seat by exhaled gases, the stem 64 having a groove 68 adjacentits bottom end which is engageable by the top coil of the spring 66 forconnecting the stem and spring together. The top wall of the housing 61has a plurality of openings 69 for discharging exhaled gases from thehousing.

The purpose of the valve 60 is to discharge exhaled gases to atmospherewhen desired, in which case the stem 64 is unscrewed so that the valve65 will be unseated by the flow of exhaled gases and permit the exhaledgases to flow through the openings 67 and 69 to atmosphere. Duringinhalation, the valve is pulled firmly into engagement on its seat. Whenthe closed system is used, the valve 60 is closed by tightening stem 64so that exhaled gases will pass through the canister.

The valve unit 17 has an oxygen connection 70 mounted in a side wallthereof. The connection 70 establishescommunication between the chamber48 and the oxygen tube 20, the connection 70 being disposed closelyadjacent the inlet valves 43 so that when oxygen is used it will beintroduced directly into the fiow of gases from valves 43 at a pointremote from outlet valves 42. Oxygen entering while inlet valves 43 areclosed, during exhalation, crowds the exhaled gases to the left side ofchamber 48 in Figure 3, adjacent outlet valves 42, to elfect ascavenging operation in each breathing cycle.

Figures 8, 9 and 10 illustrate a valve unit 17' having a slightlymodified structure from that shown in the other views. This valve is ofsmaller size and is intended primarily for small children. Similar tothe main embodiment, the valve unit 17' comprises a composite housinghaving an upper portion 21', a lower portion 22, and an intermediatewall or port -plate23'. The upperportion 21 of the housing has a pair ofparallel, longitudinal passageways 24 and 25' defined at the upperportion thereof by semi-cylindrical wall portions 26 and 27',respectively, closed at one endbya wall 28'. The other end of the unithas a wall 29 in which is mounteda pair of tube connections 30' and 31'communicating, respectively, with the passageways 24' and 25.

This structure differs from the main embodiment in that only a singleport 35' and 36' is provided in port plate 23', the flow of gasesthrough these ports being controlled by valves 42 and 43, respectively.Lower portion 22 has a chamber 48' which, as seen in dotted lines inFigure 9, has a semi-circular portion 49' slightly larger than valve 43and a semi-circular portion 50 which follows substantially the peripheryof a portion of the port 35. Wall 49' is substantially straight andvertical and the wall 50' is curved. This embodiment of the inventionhas a small bottom opening 52' arranged like the opening 52 in Figure 3to overlap portions of the ports 35 and 36, the upper portion of thewall which defines the opening 52' being rounded to provide, inconjunction with chamber 48', a stream-lined flow of gases. Opening 52is adapted to receive a connector 56 for the endotracheal tube 57.Connector 56 has a fitting 58 for the oxygen tube 2t). In thisembodiment the mechanical dead space in valve portion 22 has beenreduced to 5 cc., whereas the mechanical dead space in a conventionalY-chimney piece, which is variable according to the particular apparatusemployed, may be 25 cos.

The valve units of the present invention, therefore, provide, incombination with other equipment, an improved system for administeringanesthetic to a patient. The valve unit is disposed closely adjacent thepatients respiratory system to obviate any unnecessary dead air spacesin the mask, fittings or tubes between the patient and the valve. Asbest seen in Figure 4, almost half of each port 35 and 36 is overlappedby opening 52 and is.

substantially in a direct line with the flow of gases through theopening 52 of the mask or endotracheal tube, whereby no appreciableturbulence or resistance to flow is created in the valve, and,importantly, the valves 42 and 43 operate substantially instantaneouslyand effortlessly with the flow of gases by inhalation and exhalation.

The structure of the valves 42 and ,43 reduces the impedance to thepassage of gases to a minimum. Each of these valves is formed from aflexible rubber whereby very little energy has to be expended inovercoming the inertia in opening and closing them. This quick responseof the valves to the movement of gases prevents any appreciable reversefiow or backlash of gases which would otherwise occur just as the valvesare closing. The total cross-sectional area of the inlet ports 36 isgreater than the cross-sectional area of the subjects trachea so that noresistance to breathing will result.

An important feature of the present valve unit is the lack'of dead airspace therein whereby there is a minimum re-breathing of carbon dioxideby the patient. The depth of chamber 48 is sufficient to provide for thefree flow of gases through the valves but yet is sufficiently reduced insize to prevent any appreciable dead air space, as was pointed outhereinbefore. Therefore, anesthetic is efficiently administered to apatient with as little untreated exhaled gases as possible to produceminimal re-breathiug of the patients carbon dioxide. In persons having asmall tidal volume, the eificient operation of the present valvestructure produces improved administration of the anesthetic.

Referring to Figure 3, the housing parts 21, 22 and 23 are preferablyformed from a transparent plastic. These three portions are integrallysecured together by any suitable means, such as a transparent plasticcement, insuring a gas-tight device. Thus, the operation of the valvesmay be observed at all times and visibly tested before use to insuresafety.

To install the valves 42 and 43, the stem thereof is first inserted inthe aperture 40 of the hub 39 and the projecting end thereof is graspedby a suitable, commonly available instrument, such as tweezers or ahemostat, and sufiicient tension is then applied to the stem to lock theneck portion 46 in the aperture 40. Valves 42 are moved into placethrough the tube connection 30 and the necessary tension for locking itsneck portion 46 in the aperture 40 is applied by the instrument insertedthrough opening 52. Valves 36 are moved into place through the opening52 and the stem engaged by the instrument inserted through connection31. The valves are thereby readily replaceable when they deteriorate.

Having now described my invention and in what manner the same,may beused, what I claim as new and desire to protect by Letters Patent is:

1. A respiratory valve unit for use with a face mask or endotrachealtube comprising a wall member, parallel semi-cylindrical inlet andoutlet passageways extending along one side of said wall member, saidwall member forming one side of said passageways, tubular connectors onsaid passageways projecting parallel with said wall member, a breathingchamber on the opposite side of said wall member, an inlet port in saidwall member between said inlet passageway and said chamber, an outletport in said wall member between said outlet passageway and saidchamber, an inlet valve in said chamber on said inlet port, an outletvalve in said outlet passageway on said outlet port, and means in saidchamber for mounting said valve unit on a tubular connector on a facemask or endotracheal tube.

2. A valve unit as defined in claim 1 wherein said chamber includes awall closely spaced from said wall member and said chamber wall isprovided with a connector opening for said mask and tube overlappingportions of said inlet and outlet ports.

3. A valve unit as defined in claim 2, further including a gas inletconnected with said chamber at a point adjacent said inlet port.

4. A respiratory valve unit for use with a face mask or endotrachealtube comprising a port plate having inlet and outlet ports, a housingmember on one side of said plate forming with said plate an inletpassageway extending along said plate and communicating with said inletport and an outlet passageway extending along said plate andcommunicating with said outlet port, a housing member on the oppositeside of said plate defining a chamber in communication with both of saidports, said last housing member having a connector opening for said maskand tube closely adjacent and overlapping both of said ports, and valveson said ports.

5. A valve unit as defined in claim 4 including a gas inlet connectedwith said chamber at a point adjacent said inlet port and remote fromsaid outlet port.

6. A valve unit as defined in claim 4 including a spring loaded outletvalve on said first housing member provid ing an automatic exhalationoutlet from said outlet passageway to atmosphere.

7. A respiratory valve unit for use with a face mask or endotrachealtube comprising a port wall having inlet ports adjacent one edge thereofand outlet ports adjacent an opposite edge thereof, valves on saidports, a housing on one side of said wall forming with said wall side byside inlet and outlet passageways extending along said wall andcommunicating with said ports, respectively, external tubularconnections on said housing at the ends of said passageways, and ahousing on the opposite side of said wall forming a chamber incommunication with all of said ports and having connector means for saidmask and tube comprising a circular opening overlapping all of saidports.

8. A valve unit as defined in claim 7 including a gas inlet in saidsecond housing connected with. said chamber through the inlet port sideof said second housing.

9. A respiratory valve unit comprising a port plate having port openingstherein, a divided housing portion on one side of said plate forminginlet and outlet passageways extending along said one side of said platein communication with said port openings, inlet and outlet valves onsaid port openings, a breathing chamber on the opposite side of saidplate communicating with said port 7 openings, said breathing chamberhaving a wall parallel References Cited in the file of this patentwithsaid port plate provided with a circular opening over- UNITED STATESPATENTS lapping said port openings to receive a tubular face mask orendotracheal tube connector, and side walls on said i Mccaa 191 1927breathing chamber contoured closely around said port 5 03 233 openingsto minimize the volume of said chamber.

FOREIGN PATENTS I 937,391 France Mar. 8, 1948

